TEHRAN, Iran — Iran has denied a report that its supreme leader wrote a letter to U.S. President Barack Obama, the Islamic Republic's official news agency reported, as the country negotiates with world powers over its contested nuclear program.

"The U.S. president has a record of sending letters and in some cases Iran responded to his letters," Afkham said Sunday. Neither she nor the IRNA report elaborated on her comments, though Afkham said Iran had no immediate plans to write Obama again.

The Wall Street Journal report said Ayatollah Ali Khamenei wrote Obama in recent weeks in response to a letter by the U.S. president asking Iran to work with an American-led coalition fighting the extremist Islamic State group in Iraq and Syria.

The report said Khamenei outlined a series of abuses he said the U.S. committed against Iran in the last 60 years. However, the report also quoted an unnamed former Obama administration official suggesting it could signal a potential breakthrough in relations between the two countries, who have viewed each other with mutual suspicion since the 1979 Islamic Revolution toppled the U.S.-backed shah.

In November, Iran said it had written back in response to letters sent by Obama, the first acknowledgement in the Islamic Republic of such correspondence. However, it was not clear whether Khamenei wrote the letters himself.

U.S. and Iranian officials held a series of secret meetings in 2013 that ultimately paved the way for a historic interim nuclear deal in Geneva. Obama and Iranian President Rouhani also have had a historic telephone conversation, the first direct communication between the two nation's leaders since 1979.